The present invention relates to an automotive headlamp which is provided with a measuring device for ascertaining whether or not the rightward-leftward irradiating direction of the headlamp, namely, the irradiating angle of the lamp in the rightward-leftward direction, is in its normal and prescribed position, and which is capable of readily making adjustment, in case the irradiating angle of the headlamp is not in the prescribed position, in such a manner that the irradiating angle of the headlamp in the rightward-leftward direction may be set in the prescribed position.
A conventional automotive headlamp will be described with reference to an example of a movable-reflector type headlamp, in which a reflector is supported in a manner permitting its tilting motion within the lamp body. As illustrated in FIG. 1, the rear surface side of a reflector 402 is supported in relation to a lamp body 401 by three points, namely, by two aiming screws 403 and 404, which extends forward and rearward, and one swing support point 405. Moreover as seen in FIG. 1, which shows the reflector as seen from the front, the aiming screws 403 and 404 extend in the vertical direction. The aiming screws 403 and 404 are supported in a manner permitting their rotational motion on the rear surface wall of the lamp body 401, and the supporting point provided by the aiming screws 403 and 404 to the reflector 402 is arranged, for example, at right angles in relation to the swing support point 405. Thus, the headlamp is designed to allow adjustment of the irradiating angle of the lamp by tilting the reflector 402 around the horizontal axis Lx and the vertical axis Ly by the aiming screws 403 and 404. In this regard, reference numeral 406 indicates an electric bulb, which is a light source mounted in the reflector 402.
Also in a movable-unit type headlamp, in which a lamp body and reflector unit comprised of a reflector formed in a construction integrated with the inside circumferential surface of the lamp body is supported in a manner permitting its tilting motion in relation to the lamp housing, has a construction (though not illustrated in any figure) in which the lamp body and reflector unit is supported with one swing support point and two aiming screws, as is the case with the movable-reflector type headlamp. Thus, it is designed to permit adjustment of the irradiating angle of the lamp by tilting the lamp body and reflector unit by rotating the aiming screws.
Thus, headlamps for use on automobiles are designed to allow adjustments of their irradiating angle by tilting a tilting member provided with a light reflecting surface which sets the irradiating direction of the lamp (such a tilting member being the reflector in a movable-reflector type headlamp and a lamp body and the reflector unit in a movable-reflector unit type headlamp) in the upward-downward direction (around the horizontal axis) and in the rightward-leftward direction (around the vertical axis) in relation to the base member (such a base member being a lamp body in a movable-reflector type headlamp and a lamp housing in a movable-unit type headlamp) by rotating the two aiming screws.
Then, recently various proposals have been made to allow for easily measuring the irradiating angle of the lamp in the rightward-leftward direction. Commonly assigned U.S. patent applications, Ser. Nos. 07/370,949 and 07/508,751, unexamined Laid-Open Japanese Utility Model Application (OPI) No. Sho. 63-8397, Japanese Utility Model Application (OPI) No. Sho. 63-21576, etc., describe earlier proposals made by the present applicant.
However, the series of proposals which have been made to the present time are for a construction in which a measuring device for measuring the inclination of the tilting member in the rightward-leftward direction is provided chiefly between the tilting member and the base member, and generally wherein the installation of such a measuring device in an upper position of the lamp is done for convenience in reading the calibration on the measuring device. This presents a problem in that such an arrangement results in a larger upward-downward size of the lamp, which is contrary to the contemporary demand in favor of headlamps with a small upward-downward size. Above all, the movable-reflector type headlamps, which have such a measuring device arranged within the lamp body, present an additional problem that the construction causes inconvenience in reading the calibration.
Also, in commonly assigned U.S. patent application, Ser. No. 07/370,949 a construction having a measuring device with the calibrated part protruding into the area in the rear part of the base member is proposed, but such a construction presents the problem that it requires holes to be formed in the base member for the installation of a measuring device, which in its turn results in troublesome processing work and additionally calls for troublesome adjustment on the occasion when such a measuring device is assembled into the lamp.